Positively actuated starting device for engine



Aug. 2, 1960 fr. LAFITTE POSITIVELY ACTUATED STARTING DEVICE FOR ENGINE Filed Jan. 29, 1959 5 SheetsSheet 1 QQ .WS

Ist, IIHHHIT .wn hm. n" QS INVENTOR THEooRE LAFITTE T. LAFITTE Aug. 2, 1960 POSITIVELY ACTUATED STARTING DEVICE FOR ENGINE Filed Jan. 29. 1959 3 Sheets-Sheet 2 /NVENTOR A1184 2, 1960 T. LAFITTE 2,947,179

` PosITIvELY Ac'ruATED STARTING DEvIcE FOR ENGINE Filed Jan. 29, 1959 3 Sheets-Sheet 3 I il. ,E

, l ha 75;? 35/ A'rToRNE'V-S United. States Patent PosmvELY ACTUATED STARTING DEVICE ron ENGrNn Thodore Lafitte, 2 Villa Niel, Paris, France Filed Jan. 29, 1959, Ser. No. 789,919

Claims priority, application France Feb. 4, 1958 A5 Claims. (Cl. 74'6) My invention has for its object improvements in starters operating positively, of the type for which I have filed a copending specification under Ser. No. 687,522 on October l, 1957. Y

In the starter described in said prior'speciiication for an -electric engine-starting motor, a driving sleeve provided with helical runways slides along cooperating helicalrunways of the shaft of the electric starter and is driven into rotation by said shaft, while teeth carried by said sleeve mesh with similar teeth on one end of a drivingpinion adapted to revolve freely on the shaft of the electric motor and meshing at its other end with a gear wheel operatively connected with the shaft of the engine to be started upon compression of a spring coaxial with the starter shaft and a forked rocking lever controlling the sleeve also controls elastically a switch energizing the electric starter, the helical runways producing under the action of the starting torque of the electric starter a force parallel with the axis of the shaft which clamps the driving pinion between the driving sleeve and a stop. v

My present invention has for its object improvements in said positively acting starter, said improvements being adapted to be associated with arrangements according to my said prior specification, Ser. No. 687,522. Y

One of said improvements consists in ensuring, in. addition to a return of the driving means towards their inoperative position by a sufficient amount, chiefly as concerns the driving pinion, the interengagement between the teeth onthe driving sleeve and pinion under suitable pressure conditions, in all cases, through the agency of two springs acting in opposite directions and the size of which cuts out any possible brittleness and provides a long life for the arrangement.

A further improvement consists in returning the starting means into their `inoperative position, chiefly as concerns the driving sleeve through the agency of the ice between the teeth provided respectively on the driving sleeve and on the pinion. l

A still further improvement consists in machining inside the gear wheel rigidly connected with the engine to be started ,and preferably before the cutting of its teeth a frusto-conical joggle joint so as to dene as also for the driving pinion, teeth sections of a substantially pyramidal shape which will allow the easy interengagement between the cooperating teeth, even in the absence of the flaring teeth intervals which are `generally resorted to. 1

Other arrangements and improvements will appear in the following detailed description, reference being made to the accompanying drawings, given by way of example and by no means in a limiting sense, so as to allow a proper understanding of said improvements and arrangements. In said drawings:

Fig. 1 is a longitudinal cross-section of the starting device in its inoperative position, said starting device being `shown with the solenoid controlling it.

Fig. V2 is a part of the preceding longitudinal crosssection, wherein the starting device is shown in its terminal position engaging the yielding stop. Y J

Fig. 3 is a longitudinal cross-section of the starting device incorporating a modification of the means returning it into its inoperative position. Y

The upper half of Pig. 4 is a cross-section of a modication of the starting device in its inoperative position, while its lower half is a cross-section of said modification wherein the normally driving pinion meshes with the gear wheel when acting as a driving element. v

Figs. 5 and 6 are two sectional views of the gear wheel shown in outline.

Turningto Figs.` l and 2, the starting or driving sleeve 1 is guided over the shaft 3 by the washer 100 Vand engages the helical grooves 5 in said shaft; the sleeve 1 is provided with teeth 6 adapted to engage similar cooperating teeth 7 'formed in the driving pinion Sadapted to revolve Aover a ring 101 provided with a ange 102 spring acting on the contact-making push-member or of A still further improvement consists in maintaining the interengagement between the teeth provided on the driving sleeve and pinionby springs, preferably blade springs, which are suitably'carried by the driving pinion and are subjected through the rotation of said driving 'pinionto the action of centrifugal force to an extent .which increases together with said rotary speed as to gradually reduce and to iinally Vcut out, chiefly during overspeed stages, if required, the pressure of engagement thereby cutout either partly or totally the friction and adapted to slide and rotate over the shaft 3.V A spring 9 fitted between a stop 10 and the ring 101'urges, through the agency'of the ange 102 of the latter, the driving pinion 8 toward the driving sleeve 1 and has a tendency to maintain the teeth 6 and 7 engaged with one another. A spring 103 is fitted between the washer 100 and the ring 101 so that its thrust opposes the thrust exerted by the spring 9 and only the resultant of these two opposed thrusts acts for interengaging the teeth 6 and 7, while the return of the driving pinion 8 towards its inoperative position is ensured by the complete thrust of the spring 9.

The stop 10 is held in contact witha shoulder 104 on the shaft'3 by a spring 10S housed inside a cap 106 adapted to revolve inside a ring 107 litted inside a 'stationary carrier member 108. Said cap 106 including a ange-shaped section 109 is fitted centrally over the stop 10 and is clamped by the nut 111 with the interpo'sition of a washer 110 over the shaft 3 which is thus held with a slight clearance by the section 109 and the washer" 110 in a well defined longitudinal position with reference to the carrier member 108. The driving pinion 8 is adapted to mesh in a conventional manner with the large gear .wheel 33- rigidly connected with the engine to be started and which is located at a suitable distance from saidl end, or the like, on a pin 116 fitted transversely over the core 36 of the solenoid 35. The core 36 includes an extension formed by a rod 42 of insulating material passing through the pole-pieces 117 and adapted to act onV an elastic blade 118 constituted, as well known initheart, by'thinsuperposed elastic blades and carrying amovable contact-piece 119 cooperating .with a stationary currentfeeding contact-piece 120. The elastic blade 118 is'secured to the contact-piece 121 transmitting current to theelectric'starte'r.

In my prior specification, it has been stated that the starting device according to the invention could be controlled by any known or suitable means. The arrangement according to Figs. 1 and 2 shows an example -of such control means incorporated members similar to those used for the control system according to said prior specification.

The operation of the arrangement is as follows:

- When thesolenoid 35 is energized, the core 36 is drawn in and engages the pole-piece 117 'so as -to 'bend through its rod 42 the elastic blade 118 and to urge it rearwardly whereby the circuit is closed between the contact-pieces 119 and 120 and the starter motor 4 is thereby energized and its shaft 3 starts rotating. In the meantime, the core 36 urges through the pin 116 the forked lever 20 rearwardly so that said lever, which remains in contact with the stop 51 under the action of the spring 49' compressed thereby, rocks round the end of said stop 51 and produces through its outer cylindrical ends 113 the progression of the driving sleeve 1 forming the starting device over the shaft .3 towards the stop 10.

Two cases are now to be considered:

(a) When the teeth of the driving pinion Sand of the gear wheel 33 mesh with one another and the Vforked lever 20 is shifted from its inoperative position for which its axis lies at 122 into a position for which'its .axis lies at 123 so that the driving pinion 8 is brought vinto its position indicated by dot-and-dash lines at 124 said driving pinion is spaced from the stop by a distance which is greater than the depth of engagement between the teeth 6 and 7.

(b) If a tooth of the driving pinion `8 .abuts vagainst a tooth of the gear wheel 33 and the forked lever 20 moves from its inoperative position having for its axis 122 into an intermediate position for which its axis is located at 12S whereby the driving pinion 8 is shifted towards the gear wheel 33, as shown in dot-anddash line's at 126.

YIn this case and as precedingly, the circuit is closed 'at 119-120 by the core 36 so that the starter motor is energized, its shaft 3 revolves and drives through the sleeve 1, the driving pinion 8 which engages the gear wheel 33 and enters the position 124 at the same time as the forked lever enters the position for which it lies Vat 123, as precedingly.

The starter motor 4 continuing its rotation, the pinion 8 is urged against the stop 10 under the action of the helical groove with a force depending, under conditions remaining otherwise the same, on the slope of said grooves, on the resistance of the gear wheel 33 against rotation, on the inertia of the rotary parts and on the possibility of a rearward movement or back ring of the engine to be started.

Said thrust exerted by the driving pinion 8 on the stop 10 may be sudden and exert a substantial force, in particular in the case of a control system of a known type, as illustrated in Figs. l and 2 when the teeth of the driving pinion 8 and of the gear wheel 33 abut against each other. The shaft of the starter motor revolves then at .full `speed and produces a speedy progression of the driving pinion 8 which impinges against the stop 10, which cannot occur with the control system described in `my prior specification. The importance of the shock thus exerted may be considerably increased in the Case of a back'ring of the engineto be started.

With a yview to protecting in all cases the parts-of vthe starter motor and of the starting device against the effect of such shocks, the stop 10 is urged by the spring 105 subjected to a suitable suiciently large initial stressing against the shoulder 104; when the thrust exerted by the driving pinion 8 acting coaxially on the stop 10 is higher than this preliminary stressing, the stop 10 reeedes and compresses the spring until it engages the flange 109 on the cap 106, as shown in Fig. 2.

The shocks are thus damped either entirely or partly, whereby the parts to be considered are protected against the destructive effect of such shocks.

On the other hand, during the sliding of the stop 10, the latter is lheld energetically in contacting relationship with the driving pinion 8 which is centered by said stop, so that during the possible variations of the driving stress, the catch system which is not released is not operative and its wear is consequently reduced.

During its movement towards the stop 10, the driving sleeve 1, urged forwardly along the helical grooves 5, pushes the forked lever 20 through its ends engaging the annular groove 114; said lever 20 enters thus the position shown yat 127 in Fig. 2, for which it remains in engagement with the stop 51 and compresses the spring 49 after moving over the pin 116 which continues guiding it. When the action of the solenoid 35 ceases and current to the starter motor is stopped, the suitably gauged spring 49 returns the forked lever 20 and consequently the driv- `ing sleeve 1 into 'their inoperative position illustrated in Fig. 1.

In my prior above-mentioned specification, the spring returning the driving pinion 8 which is coaxial with the starter shaft, played two parts, to wit: on the one hand, it served as a clutch spring and, on the other hand, it returned the driving pinion into its inoperative position.

According to my present invention, the pinion-returning spring 9 which is suitably gauged for it to execute the desired operations, acts in opposition to a further spring 103. The latter engages the ring 101 which is preferably mounted loose on the shaft 3 inside the driving pinion 8 and opposes the thrust of the spring 9 whereby the ange 102 on said ring engages the driving pinion 8 with the resulting force produced by the cooperation of the two springs 9 and 103. Said resulting force increases when the driving pinion 8 moves from its inoperative position towards its position engaging the stop 10.

In order that the engagement betweenthe teeth 6 and 7 may be performed under satisfactory conditions, it is sufficient to suitably select the minimum tensioning l1f and the maximum tensioning T to be borne 'by said teeth. The slope of the curve showing the flexibility of the spring 9 when the stroke of the pinion 8 is assumed to be equal to C, for a depth h of engagement between the teeth 6 and 7 and a release by 1 mm. of said engagement, is dened by the equation:

Fa-#Tera The spring 103 is designed as a function of the stress returning the sleeve 1 against the stop 112, which stress is to be provided by the spring 9.

This arrangement incorporating two springs, mounted in opposed relationship, may also be applied when the driving pinion 8 is ring-shaped in the conventional manner.

It is also possible, when the pinion 8 is urged back by other means, to resort to a clutch spring coaxial with the shaft 3, providing the stresses t and T to be exerted on said pinion.

Fig. 3 shows an arrangement in which the starting sleeve 1 -is urged back against the stop 112, solely Vunderthe action of a pusher spring 67 or the like. In Vsaid yarrangement, the ring 78 over which the driving pinion 8 is revolubly carried carries an expansion or collar 79 coaxial with the driving sleeve 1, the groove f114 of which is engaged by the cylindrical ends of the forked rocking beam 20 which, 'is suspended tothe pin 116 rigid with -the core s6 ofthe solemn, which limer is not illustrated. The ring 78l is rrigidly secured to the driving sleeve I either by a screw 128 or any other means.

-`O ver the end of the ring 78 is centrally arranged the clutch spring 9 of 'which one end is secured through any -suitable means inside a recess 129 provided in said ring 78 while its other end engages the driving pinion 8 so as to ensure the interengagement between the teeth of said driving pinion `8 and those of the driving sleeve 1.

When the solenoid isenergized, its core 36 returns as precediiigly described the starting device in-to its operative position. When the solenoid is deenergized, the forked rocking beam bearing Iagainst the stop 68 will, under the action of the thrust of the spring 67, disengage the driving pinion 8 while returning the lstarting or driving sleeve against the stop 112.

In Fig. 4, a dished member `130 to which are riveted blade springs 131 is Vsuitably secured to the driving pinion 8. IheV spring blades 131 which are preferably provided with Ysmall bearing blocks 132 engage the frusto-conical surface 133 formed on the ydriving sleeve 1, with an energy sufficient for ensuring the engagement between the teeth 6 and 7 provided on the driving pinion 8 and on the driving sleeve so as to form an operative clutch. The driving pinionS is centrally carried by the shaft 3, with the interposition of a loose ring 101 urged forwardly by a return spring 9 engaging the stop 10 provided to the front thereof. `The starting sleeve, when inoperative, is returned onto the ystop 112 by the spring 9 land by the forked rocking beam which is not illustrated. Y

A clearance I of a suflicient depth which is larger than the depth of the teeth 6V and 7 is provided between the pinion 8 and the flange 102 of the ring 101.

The lower part of Fig. 4 shows cross-sectionally the gear wheel 33'acting as a driving member and engaging the driving pinion 8, which is thus caused to rotate at a speed increasing gradually with the speed of the engine. Said speed may in fact reach speedily the range of overspeeds. Y

As a consequence of .the rotation of the driving pinion 8, the springs 131 and the intermediate blocks 132 are subjected to a centrifugal force which increases with the speed of rotation so as Ito provide for a gradual straightening of lthe springs 131 and to urge the latter for instance against the inner surface of `the dished member 130 `whereby the pressure of engagement is reduced gradually and is finally cut out whereby the driving pinion 8 is allowed to move away from the driving sleeve 1, to an extent suicient for it to revolve without any substantial friction between the teeth 6 and 7, in particular for overspeed conditions, which is a very important result ensuring a long life without any Isubstantial wear for said teeth. When the starting sleeve returns into its inoperative position after deenergization, the rotation of the driving pinion 8 is at an end and the blade springs 131 return into'their clutch-operating position.

Driving pinionsV such as 8 have already been described which include a frusto-conical joggle joint such as 93 which cuts into the teeth and denes with the flanks of the teeth and thel front surface of the latter merging along an arc of a radius R with the outer cylindrical tooth surface, tooth sections 134 having a substantially pyramidal shape whichallow as explained hereinabove, an easy engagement between the cooperating teeth. ,Y Saidarrangement is resorted to as shown in Figs. 5 and 6 -for the teeth of the ygear wheel 33, the cross-sections of which tare shaped with an oblique joggle joint surface 135 in Fig. 5, or else with a curvilinear joggle joint, as

shown Iat 136 in Fig. 6. These joints are advantageously machined on the lathe before the cutting of the teeth. The teeth sections 137 and 138 thus defined are similar to the teeth sections 134 which are bonded on the driving pinion 8 by the frusto-conical joggle joint surface 93, so that the driving pinion 8 meshes readily with the gear wheel 33, even in the absence of the conventionally used flaring tooth anks.

The preceding -arrangements may be advantageously associated with the means controlling the starting sleeve through a forked rocking beamthe operation of which has been disclosed hereinabove and in the prior specification.

Obviously, the present improvements are given solely by way of exempliiication and by no means in a binding sense and they may incorporate modifications, additions and allow omissions and be associated together or separately with any similar arrangement including a part of the apparatus disclosed in my prior specification.

What Lclaimis:

1. A device for starting an engine, comprising an eleci tric starter motor, a shaft connected to said motor for being driven thereby and provided with at least one helical guideway, a driving sleeve rotating coaxially with said shaft and provided with at least one inner helical guideway engaging the corresponding helical guideway ony the said shaft, a washer carrying said sleeve and sliding therewith over said shaft for guiding said sleeve, a ring rotatably and slidingly mounted on saidshaft, a driving pinion concentrically carried by said ring, cooperating clutch teeth formed on the surfaces facing each other of said driving sleeve and said driving pinion, a further series of teeth at the end of said driving pinion facing away from said driving sleeve, a gear wheel operatively connected with the engine to be started and adapted to mesh with the last-V mentioned teeth on said driving pinion, a spring arranged coaxially with reference to said shaft of said starter motor and urging said cooperating teeth on said driving pinion and on said driving sleeve into engagement, a second spring arranged coaxially with reference to said shaft acting in opposition to said first-mentioned spring and tted between said ring and said washer guiding said driving sleeve, a resilient stop for said driving pinion adapted to engage the surface of said driving pinion facing away from said driving sleeve when said pinion is engaging said gear wheel, a forked rocking lever having one end engaging said driving sleeve for moving the latter over said shaft co-aXially with the shaft axis from lan inoperative position towards an operative position engaging said driving pinion, a return spring acting on said rocking lever urging the same back into its inoperative position, means for moving the other end of said lever against said return spring, a switch for being closed by said rocking lever when in its operative position, an electrical circuit controlled by said switch for energizing said starter motor, with the starting torque of said motor causing said shaft to exert a longitudinal thrust on said driving sleeve, clamping said driving pinion between said driving sleeve and said stop.V

2. A device for starting an engine, comprising an electric starter motor, a shaft connected to said rnotor for being driven thereby and provided with 'at least one helical guideway,`a driving sleeve rotating coaxially with said shaft and provided with at least one inner helical guideway engaging the corresponding helical guideway on said shaft, a drivingpinion revolubly and slidingly carried by said shaft, cooperating clutch teeth formed on the surlfaces facing/each ,other of said driving sleeve and said driving pinion, a further series of teeth at the end of said driving pinion facing away from said driving sleeve, a gear wheel operatively connected with the engine to be started andadapted to mesh with the last-mentioned teeth on said drlvrng pinion, a spring arranged coaXially with reference to'sald shaft land urging said cooperating teeth of said driving pinion and said driving sleeve into engagement, a forked rocking lever having one end engaging said driving sleeve for moving the latter over said shaft co-axially with the shaft axis from an inoperative position towards an operative position engaging said driving pinion, a return spring acting on said lrocking lever urging the same badk into its inoperative position, a switch for being closed by said rocking lever when in its operative position, mem

for moving the otherend of said lever against said return spring, an electrical circuit controlled iby .said switch for energizing said starter motor with starting torque of said motor causing its shaft to exert a longitudinal thrust on said driving sleeve and thereby on said driving pinion, and astop annularly surrounding said shaft, a bearing for said shaft and means yieldingly connected said stop with said bearinglto .allow a slight collapsing of said stop upon impact against the Vlatter of said driving pinion when being urged `forwardly into engagement with said gear wheel [through the second series of teeth thereon, by the longitudinal thrust exerted on said sleeve and pinion.

3. A device for starting an engine, comprising an electric starter motor, a shaft connected to said motor for being driven thereby and provided with at least one helical guideway, aV driving sleeve rotating coaxially with said shaft and provided with at least one inner helical guideway engaging the corresponding helical guideway on said shaft, a driving pinion revolubly and slidingly carried by said shaft, cooperating clutch teeth formed on the surfaces facing each other of said driving sleeve and said driving pinion, a further series of teeth at the end of said driving pinion, facing away from said driving sleeve, a gear wheel operatively connected with the engine to be started and adapted to mesh with the last-mentioned teeth on said driving pinion, a spring arranged coaxially with reference to said shaft and urging the cooperating teeth of said drivingpinion and said driving sleeve into engagement, spring blades rigidly connected to said driving pinion to rotate in unison therewith and adapted to engage 'through their free ends cooperating surfaces on said driving sleeve to urge the latter into engagement through its teeth with the cooperating teeth on said driving pinion, said blade springs being urged outwardly into an inoperative position by centrifugal force upon a speed of rotation of said driving pinion adapted to engage its surface facing away from said driving sleeve when said pinion is engaging said gear wheel, a forked rocking lever having one end engaging said driving sleeve and for moving the latter over said shaft co-axially with the shaft axis from an inoperative position towards an operative position engaging said driving pinion, -a `return spring acting on said rocking lever urging the same back into its inoperative position, means for moving the other end of said lever against said return spring, a switch for being closed by said rocking lever when in its operative position, an electrical circuit controlled by said switch for energizing said starter-motor with the starting torque of said motor causing its shaft to exert a longitudinal thrust on said driving sleeve for clamping said driving pinion between said driving sleeve and said stop.

4. A device for starting an engine, comprising an electric starter motor, a shaft connected to said motor for being driven thereby and provided with at least one helical guideway, a driving sleeve rotating coaxially with said shaft and provided with at least one inner helical guideway engaging the corresponding helical guideway on said shaft, a driving pinion revolubly and slidingly carried by said shaft, cooperating clutch teeth formed on the surfaces facing each other of said driving sleeve -and said driving pinion, a further series of teeth at the end of said driving pinion facing away from said driving sleeve, a gear wheel operatively connected with the engine-to be started and adapted to mesh with the lastmentioned teeth on said driving pinion, said gear wheel being provided with a frusto-conical joggle joint giving the teeth thereof a substantially pyramidal shape, a

spring arranged coaxially with reference to said shaft and urging the cooperating teeth of said driving pinion and said driving sleeve into engagement, a second spring arranged coaxially withreference to said shaft and acting in opposition to said first-mentioned spring and fitted between said driving pinion and said driving sleeve, a stop for said driving pinion adapted to engage its surface facing away from said driving sleeve when said pinion is engaging said gear wheel, a forked rocking lever having one end engaging said driving sleeve and for moving ythe latter over said shaft co-axially with the shaft axis from an inoperative position towards an operative position engaging said driving pinion, va return spring acting on said rocking lever to urge same back into its inoperative position, means for moving the other end of said lever against said return spring, a switch for being closed by said rocking lever when in its operative position, an electrical circuit controlled by said switch for energizing said starter motor with the starting -torque of said motor causing said shaft .to exert a longitudinal thrust on said driving sleeve for clamping said driving pinion between said driving sleeve and said stop.

5. A device for starting an engine, comprising an electric starter motor, a shaft connected to said motor for being driven thereby and provided with at least one helical guideway, a driving sleeve rotating coaxially with said shaft and provided with at least one inner helical guideway engaging the corresponding helical guideway on said shaft, a ring xedly connected to said driving sleeve and being rotatably and slidingly mounted on said shaft, a driving pinion concentrically carried by said ning, cooperating clutch teeth formed on the surfaces facing each other of said driving sleeve and said driving pinion, a further series of teeth at the end of said driving pinion facing away from said driving sleeve, a gear wheel operatively connected with the engine to be started and adapted to mesh with the last-mentioned teeth on said driving pinion, a spring connected to said ring arranged coaxially with reference to said shaft for urging the cooperating teeth of said driving pinion and said driving sleeve into engagement, a stop for said driving pinion and said ring adapted to engage the surfaces lthereof facing away from said driving sleeve when said pin-ion -is engaging said gear wheel, a forked rocking lever having one end engaging said driving sleeve for moving the latter and said ring over said shaft co-axially with the shaft axis from an inoperative position towards an operative position engaging said driving pinion, a return spring acting on said rocking lever to urge same back into its inoperative position, means for moving the other end of said lever against said return spring, a switch for being closed by said rocking lever when in its operative position, an electrical circuit controlled by said switch for energizing said starter motor with the starting torque of said motor causing said shaft to exert a longitudinal thrust Von said driving sleeve for clamping said driving pinion between said driving sleeve and said stop. 

